To regenerate a particulate filter or a NOx-storage catalytic converter, which are increasingly used in modern exhaust systems, it is sometimes necessary, in a lean mixture engine, to enrich the exhaust gas with an oxidizable substance. For this purpose, a fuel vaporization unit is known from document EP 1 369 557 A1, which is arranged upstream of a particulate filter having an oxidation catalytic converter or a NOx-storage catalytic converter connected upstream thereof. The fuel vaporization unit introduces vaporous fuel into the exhaust gas flow upstream of the particulate filter or the NOx-storage catalytic converter at specific points in time. This known vaporization unit has an elongated housing that threadably receives a sheathed-element glow plug, the glowing filament of which serves as a heating element for vaporizing the fuel. To this end, the glow tube of the sheathed-element glow plug surrounding the glowing filament projects into a vaporization chamber for the fuel. A disadvantage in the known configuration is that the threaded connection between the sheathed-element glow plug and the housing of the vaporization unit constitutes a potential leakage point.
In comparison therewith, the invention provides a vaporization device of the type initially mentioned, which when compared to the prior art is distinguished by an improved tightness and low manufacturing costs.